I believe that there is often a misconception on lower the temp. the better
For a reef, temp of not more than 30 degrees or 1 degree below the border is all right.
I set my tank's temp. at 28 degrees and the everything is doing fine and some of the mushies are even splitting
In fact, I've read a post in RC that low temperatures may slow down biological catalytic reactions and cause corals to slowly die off